The present disclosure relates to a display device and a method of manufacturing the same, a method of repairing a display device, and an electronic apparatus.
Recently, organic electroluminescence display devices (organic EL display devices), which are one type of flat panel display and use an organic electroluminescence (EL) phenomenon to display an image, have attracted attention. Since a light-emitting phenomenon of organic EL elements themselves is used, organic EL display devices have superior characteristics such as a wide viewing angle and low power consumption. Furthermore, organic EL display devices have been put into practice in the video field due to their high response to high-definition and high-speed video signals. In addition, in organic EL display devices, a plastic substrate, in particular, a plastic film substrate may be used as a substrate owing to flexibility which is an intrinsic property of an organic light-emitting material. As a result, organic EL display devices attract attention as a flexible display device.
Among methods of driving an organic EL display device, an active matrix method in which a drive circuit is configured from a thin film transistor (TFT) has superior response and resolution to those of a passive matrix method. Therefore, it is considered that the active matrix method is particularly suitable for the organic EL display devices. An organic EL display device using the active matrix method includes a light emitting portion and a first panel in which light emitting elements, composed of drive circuits for driving the light emitting portion, are arranged in a two-dimensional matrix. The light emitting elements are interposed between the first panel and a second panel, which is a sealing panel. In addition, the light emitting portion has a structure in which a first electrode, an organic layer having a light emitting layer, and a second electrode are laminated.
There are two types of organic EL display devices, a bottom emission type in which light is emitted from the light emitting elements toward the first panel and a top emission type in which light is emitted from the light emitting elements toward the second panel. The top emission type organic EL display device has an advantageous effect of high aperture ratio.
In the top emission type organic EL display device, the second electrode which is located on the second panel side is a so-called common electrode shared by plural light emitting elements, and is formed of a light-transmissive conductive material such as Indium Zinc Oxide (IZO). However, such a light-transmissive conductive material has electrical resistivity which is higher than that of a general metal material or the like by two or three digits. As a result, there is a problem in that a voltage, applied to the second electrode, is not uniform in a plane of the second electrode, the luminance of the light emitting elements varies depending on positions, and display quality deteriorates.
In order to solve such problems, for example, Japanese Unexamined Patent Application Publication No. 2002-318556 discloses a technique in which an auxiliary electrode (auxiliary wiring), connected to the second electrode, is formed on an insulating layer formed on the first electrode. The auxiliary electrode is formed of the same material as that of the first electrode. In the technique disclosed in Japanese Unexamined Patent Application Publication No. 2002-318556, when the first electrode and the auxiliary electrode are formed of, for example, aluminum (Al) or an Al alloy, a surface of the auxiliary electrode is likely to be oxidized in the manufacturing process of an organic EL display device. When the auxiliary electrode is oxidized and a part of the second electrode (second electrode extending portion) is formed on the auxiliary electrode, a contact resistance between the auxiliary electrode and the second electrode increases, which leads to a voltage drop. The power consumption of the display device is increased due to the voltage drop.
International Publication No. WO 2007/148540 discloses a technique in which a contact portion is formed on the same layer as that of a drive circuit. The contact portion is formed of a conductive material of which a surface is not easily oxidized and which has a superior ohmic contact with the second electrode. A top portion of the contact portion is in contact with an end of the auxiliary electrode. The second electrode extending portion is formed over a range from the top portion of the contact portion to an upper area of the auxiliary electrode.
When foreign conductive materials are incorporated into the organic layer, there is a concern that the first electrode and the second electrode may be short-circuited due to the foreign materials. Means for solving such a problem is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2011-034849. Specifically, an organic EL display device disclosed in Japanese Unexamined Patent Application Publication No. 2011-034849 includes: an insulating substrate; a pixel electrode that is arranged above the insulating substrate; a partition wall that is arranged in the vicinity of the image electrode; a division layer that is connected to the partition wall, is arranged above the pixel electrode, and divides a portion of the pixel electrode, exposed from the partition wall, into plural regions; an organic layer that is arranged above the pixel electrode and the division layer; a counter electrode that covers the organic layer and the partition wall; and a groove that is formed on the organic layer and the counter electrode in a loop shape and exposes a part of the division layer.
When foreign materials are incorporated into the organic layer formed above the pixel electrode (first electrode), the division layer is irradiated with laser; and the organic layer and the counter electrode (second electrode), laminated above the division layer and the partition wall, are removed such that a region, into which the foreign materials are incorporated, is surrounded by a removed portion. The removed portion forms the groove. A potential is not supplied to a portion of the counter electrode (second electrode) surrounded by the groove. Therefore, this portion forms a dark spot region and the other portion substantially forms a light emitting region (for example, refer to paragraph [0050] and FIGS. 8 and 9 in the specification of Japanese Unexamined Patent Application Publication No. 2011-034849).